1. Field of the Invention
The present invention relates to an improved channel member and bearing plate assembly, in particular, to a channel member and a bearing plate capable of supporting a large area of a mine roof.
2. Prior Art
In underground mining, excavation and tunneling operations, it is conventional practice to support the overhead and lateral rock strata by elongated structural members such as metal roof mats and channel members that extend transversely across the mine roof and downwardly along the lateral side walls. The mats and channel members are provided in various lengths with holes spaced at a preselected distance apart through the members to conform to a conventional roof bolt plan. Roof bolts extend through the holes in the channel members and into holes drilled in the rock strata and are anchored in the strata to maintain the channel members compressed against the surface of the rock strata.
Bearing plates such as that disclosed in U.S. Pat. No. RE. 35,902 to Calandra, Jr. et al. typically are seated in overlying relation with the channel member so the compressive forces of the roof bolt are distributed by the bearing plate across the channel member. The surface of the bearing plate does not extend beyond the surface of the channel member.
In certain geological conditions, a large area of the mine roof must be supported by channel members. Conventional channel members which are typically about 5 inches wide are insufficient to support large areas of the mine roof or lateral side walls. In those conditions, wood timbers are used but they are bulky, cumbersome and expensive due to the increasing price of lumber. Accordingly, a need remains for wider channel members and/or complementary wider bearing plates which can support a greater area of a mine roof.